Cyclopentadienyl-type ligands have been used to prepare organometallic complexes which, in turn, are useful in such applications as olefin polymerizations, alkene isomerizations and hydrogenations.
More recently, the use of phospholes to prepare phospholyl-type organometallic complexes has been disclosed.
The use of phospholyl-type complexes (and "mixed" cyclopentadienyl/phospholyl complexes--i.e. a complex having a cyclopentadienyl and a phospholyl-type ligand) is disclosed in U.S. Pat. No. 5,434,116 (Sone, to Tosoh), published European Patent Office (EPO) applications 617,052 (Aoki et al, to Asahi), and EPO 741,145 (Katayama et al, to Sumitomo) and Patent Cooperation Treaty (PCT) application 95/04087 (de Boer et al, to Shell).
It is also known to prepare "bridged and substituted" cyclopentadienyl-type ligands--as disclosed, for example, in U.S. Pat. Nos. 5,563,284; 5,565,396, and 5,554,795 (Frey et al), U.S. Pat. No. 5,324,800 (Welborn). These "bridged" cyclopentadienyls form catalyst systems for olefin polymerization when activated by a "substantially non-coordinating anion" (as disclosed by Hlatky and Turner in U.S. Pat. Nos. 5,153,157 and 5,198,401) or an alumoxane.
However, there is no known teaching of any process to prepare ligands having a cyclopentadiene-type group which is bridged to a phosphole.